Data processing systems are known where a plurality of display systems communicate with a central host computer. These display systems typically include a base unit which acts as a display and supports a keyboard for operation as a keyboard/display terminal that communicates with the host via a controller. The terminal may interface with a plurality of features connected thereto such as a card reader or a light pen. The base unit and the features receive transmission from the controller via a feature bus in the base unit and also transmit to the controller via this feature bus. The base unit also provides priority control in permitting features to respond to a controller poll. Commands are also directly addressable to the base unit and features by the controller. Typical of such systems are the IBM 3270 information display system, the IBM 3274 control unit and the IBM 3278 display stations.
In such systems, the display stations are used to access data and run programs on the host. Storage of data or printing a hard copy typically are accomplished using bulk storage media or printers associated with the host computer. These may not always be readily accessible or available to a display station operator. Moreover, some data may be sensitive or confidential, and the operator may desire to exercise direct control over the bulk storage media on which the data is stored or the hard copy produced by the printer. Current display stations do not provide this access or flexibility. Recently, small desk top or so-called personal computers have been introduced on the market. These typically include a system unit containing a microprocessor, read only storage (ROS), random access memory (RAM), and various adapters connected to the system unit bus to allow connection of a keyboard, a CRT display, one or more floppy diskette drives, possibly one or more hard disk drives, and a printer. A personal computer would provide the display station operator with accessibility to both bulk storage media, in this case a floppy diskette, and a printer, but to simply provide the display station operator with a personal computer would be a duplication of equipment and no ability to use host files on the personal computer and vice versa.
It is therefore an object of this invention to provide a personal computer attachment for a display station that will allow the display station operator to operate the display station in either a host mode or a personal computer mode without duplication of equipment.
It is another object of the invention to provide a personal computer attachment for the display station that will allow transfer of files between the host and the personal computer and vice versa.